Esophageal stent with valve

ABSTRACT

A stent comprised of a valve and a scaffolding structure having components configured to allow at least a portion of the stent to decrease in diameter in response to an axial force applied to the stent. Further, the components and elements of the stent may be configured to balance transverse forces applied to the stent, thus reducing the incidence of infolding.

RELATED APPLICATIONS

The present application is a continuation of copending U.S. applicationSer. No. 13/285,358, filed on Oct. 31, 2011 and titled, “EsophagealStent With Valve,” which is hereby incorporated by reference in itsentirety.

TECHNICAL FIELD

The present disclosure relates generally to devices configured to beimplanted within a body lumen. More particularly, the present disclosurerelates to stents or similar prosthetic devices which, in certainembodiments, are configured to be disposed within the esophagus andwhich may comprise a valve.

BRIEF DESCRIPTION OF THE DRAWINGS

The embodiments disclosed herein will become more fully apparent fromthe following description and appended claims, taken in conjunction withthe accompanying drawings. These drawings depict only typicalembodiments, which will be described with additional specificity anddetail through use of the accompanying drawings in which:

FIG. 1 is a perspective view of a stent.

FIG. 1A is a close up view of a portion of the stent of FIG. 1.

FIG. 1AA is a further close up view of a portion of FIG. 1.

FIG. 1B is a second close up view of a portion of the stent of FIG. 1.

FIG. 1C is a third close up view of a portion of the stent of FIG. 1.

FIG. 1D is a fourth close up view of a portion of the stent of FIG. 1.

FIG. 1E is a fifth close up view of a portion of the stent of FIG. 1.

FIG. 2 is a front view of another embodiment of a stent.

FIG. 2A is a top view of the stent of FIG. 2, taken through line 2A-2A.

FIG. 2B is a cross-sectional view of the stent of FIG. 2, taken throughline 2B-2B.

FIG. 3 is a partial perspective view of another embodiment of a stent.

FIG. 4A is a perspective view of a valve for use with a stent.

FIG. 4B is a second perspective view of the valve of FIG. 4A.

FIG. 4C is a top view of a the valve of FIG. 4A.

FIG. 4D is a cross-sectional view of the valve of FIG. 4C, taken throughline 4D-4D.

FIG. 5 is a side view of a stent in an unexpanded state. Moreparticularly, FIG. 5 is a side view of an unexpanded stent in a “rolledout” state, depicted as if the stent were cut in the longitudinaldirection and rolled out flat such that the entire circumference of thestent may be viewed flat.

FIG. 5A is a close up view of the stent of FIG. 5.

FIG. 5B is a second close up view of the stent of FIG. 5.

FIG. 5C is a third close up view of the stent of FIG. 5.

FIG. 5D is a fourth close up view of the stent of FIG. 5.

FIG. 6 is a cross-sectional view of a stent disposed within a bodylumen.

DETAILED DESCRIPTION

A stent may be configured with a support or scaffolding structure thatmay optionally be coupled to a covering. Additionally, the stent maycomprise a variety of components, and the parameters of thesecomponents—such as shape, length, thickness, position, etc.—may beconfigured to provide a stent with certain properties. For example, thestent may be configured to distribute transverse loads or to changeshape in response to certain forces. In some embodiments, the stent mayalso include a suture which may aid the user with repositioning orremoval of the stent. Furthermore, the stent may comprise a valve whichmay be coupled to the inside diameter of the stent.

Though many of the examples provided herein refer to stents configuredfor use within the esophagus, the present disclosure is also applicableto a variety of stents designed for a variety of applications—forexample, biliary stents.

It will be readily understood with the aid of the present disclosurethat the components of the embodiments, as generally described andillustrated in the figures herein, could be arranged and designed in avariety of configurations. Thus, the following more detailed descriptionof various embodiments, as represented in the figures, is not intendedto limit the scope of the disclosure, but is merely representative ofvarious embodiments. While the various aspects of the embodiments arepresented in drawings, the drawings are not necessarily drawn to scaleunless specifically indicated.

The phrases “connected to,” “coupled to,” and “in communication with”refer to any form of interaction between two or more entities, includingmechanical, electrical, magnetic, electromagnetic, fluid, and thermalinteraction. Two components may be coupled to each other even thoughthey are not in direct contact with each other. For example, twocomponents may be coupled to each other through an intermediatecomponent.

The terms “proximal” and “distal” refer to opposite ends of a medicaldevice. As used herein, the proximal end of a medical device is the endnearest a practitioner during use, while the distal end is the oppositeend. For example, the proximal end of a stent refers to the end nearestthe practitioner when the stent is disposed within, or being deployedfrom, a deployment device. For consistency throughout, these termsremain constant in the case of a deployed stent, regardless of theorientation of the stent within the body. In the case of an esophagealstent—deployed through the mouth of a patient—the proximal end will benearer the head of the patient and the distal end nearer the stomachwhen the stent is in a deployed position.

FIG. 1 is a perspective view of one embodiment of a stent 100. In theillustrated embodiment, the stent 100 has a substantially cylindricalshape and defines a proximal end 102 and a distal end 104. The stent 100may include a scaffolding structure 110 formed of multipleinterconnected segments, a covering 130 coupled to the scaffoldingstructure 110, a suture 135, and a valve 150.

The scaffolding structure 110 may be comprised of any material known inthe art, including memory alloys. In some embodiments the scaffoldingstructure 110 may be constructed of nitinol, including ASTM F2063. Thethickness of the scaffolding structure 110 may be from about 0.30 mm toabout 0.6 mm, or greater; in some embodiments including thicknesses fromabout 0.35 mm to about 0.55 mm, thicknesses from about 0.40 mm to about0.50 mm, and thicknesses of about 0.47 mm.

The scaffolding structure 110 may be formed of multiple annular segmentsor rings 112 arranged in rows along the longitudinal direction of thestent 100. Each annular segment 112 may be comprised of interconnectedstrut arms 114. In the illustrated embodiment, the strut arms 114 areconnected such that they form a zigzag pattern, the pattern definingalternating “peaks” and “valleys,” around the annular segment 112. Insome embodiments adjacent strut arms 114 will form acute angles relativeto each other. Adjacent annular segments 112 may be coupled to eachother by connectors 120.

The stent 100 may further be configured with a valve 150. In someembodiments, such as the embodiment of FIG. 1, the valve 150 may becoupled to the inside diameter of the stent 100. Thus, the valve 150 isnot directly visible in the illustration of FIG. 1, though its positionis indicated by a reference line.

In some embodiments the stent 100 may be divided into one or more zonesalong the longitudinal length of the stent 100. For example, a stent 100may be configured such that different segments or zones of the stenthave different structural or geometric features or components. Forexample, the stent 100 shown in FIG. 1 may be separated into threelongitudinal zones or segments: a proximal zone, α; a transition zone,β; and a valve zone γ. In some embodiments a stent 100 may be designedsuch that the proximal zone α is relatively “softer” (meaning morecompressible in a transverse direction) than the valve zone γ. In someapplications, the relative softness of the proximal zone may beconfigured to cause less trauma to tissue which contacts an implantedstent 100. Further, the softness of the proximal end may be configuredto aid in the removal or repositioning of the stent 100. Analogously, a“harder” valve zone γ may provide additional structure and support toprevent deformation or collapse of the valve 150. Furthermore, in someinstances, the valve zone γ may be configured to be positioned at aparticular physiologic position, such as the lower esophageal sphincterin the case of an esophageal stent. The hardness of the valve zone maybe configured to resist deformation by strictures of other physiologicfeatures or conditions at the therapy site. Finally, the transition zoneβ may be configured as an intermediate zone, with properties configuredto fall between those of the proximal zone α and the valve zone γ.

FIG. 1A is a close up view of a portion of the proximal zone α of thestent 100 of FIG. 1. FIG. 1A includes portions of three adjacent annularsegments, designated 112 a, 112 b, and 112 c. Throughout thisdisclosure, particular examples of components may be designated by aletter following the reference numeral. For example, reference numeral112 refers generally to the annular segments of the stent 100. Specificannular segments, such as those shown in FIG. 1A, are thus labeled 112a, 112 b, and 112 c. This pattern of identifying particular examples ofgeneral or repeating components may be used throughout this disclosure.

In the illustrated embodiment, each annular segment 112 a, 112 b, 112 cincludes multiple strut arms 114, which are arranged in zigzag patterns.For example, strut arm 114 a is coupled to strut arm 114 b, such thatthe two arms 114 a, 114 b form a peak in the zigzag pattern. Strut arm114 b is further coupled to strut arm 114 c such that the two arms 114b, 114 c form a valley in the zigzag pattern.

In the illustrated embodiment, adjacent strut arms, such as arms 114 a,114 b, are coupled at an apex, such as apex 115 a. The angle formed atthe apexes 115 by two adjacent strut arms 114 may be designed to providethe stent 100 with particular properties. For example, in theillustrated embodiment the angle formed at each apex 115 is about 45degrees. In other embodiments this angle may be from about 30 degrees toabout 60 degrees including angles from about 40 degrees to 50 degrees.As discussed in more detail below, apex 115 angles of about 45 degrees,as well as angles within the aforementioned ranges, may aid withbalancing forces in the X and Y directions on the stent 100 to preventinfolding of the stent.

As used herein, infolding refers to inward protrusions or wrinkles thatmay form along the inside diameter of a stent in response to unbalancedtransverse compressive forces on the stent. For example, an esophagealstent may infold as a result of the peristaltic motion of the esophagus.In other instances, a stent may infold due to forces exerted by anuneven portion of the body lumen, such as a stricture or buildup of scartissue.

Furthermore, a cylindrical stent may define a set of transverse planeslocated perpendicular to the longitudinal axis of the stent. As usedherein, transverse forces are forces acting in any of these planes.Further, as used herein, the X and Y directions refer to a coordinatesystem in any of these planes. A stent designed to generally balancecompressive forces in the X and Y directions may tend to resistinfolding. In other words, a stent may have compressive forces appliedunevenly in different transverse directions. The design of the stent maybe configured to transfer these forces such that the stent distributesthe load more evenly around the circumference of the stent. Inparticular, the approximately 45 degree angles between adjacent armstruts 114 in stent 100 may transfer uneven loads further allowing thestent 100 to resist infolding. Likewise, other angles disclosed hereinmay also distribute transverse forces.

In some embodiments, the inner surface of the apex 115 may besubstantially circular or semi-circular in shape, forming an innerradius 116. The inner radius 116 of the apex 115 may be sized so as toimpart particular characteristics to the stent 100. For example, asillustrated in FIG. 1AA, the radius 116 a may be large as compared tothe angle formed by the two inner surfaces of the coupled strut arms 114d, 114 e. In such instances, the inner surfaces of the strut arms 114and the radius 116 may form a rough “keyhole” shape. In otherembodiments, the radius 116 and strut arms 114 may not form a keyholeshape, though the radius 116 is still relatively large. Designs thatincorporate relatively large radii 116 may provide desiredcharacteristics to the stent 100, such as surface finish, fatigue life,and fracture resistance. The size of the radius 116 may vary dependingon the desired properties of the stent 100. In some embodiments theradius 116 may be from about 15 microns to about 95 microns includingembodiments where the radius is from about 30 microns to about 80microns or from about 45 microns to about 65 microns.

Moreover, in certain embodiments, the stent 100 may be designed withdifferent radii 116 in different portions of the stent 100. In someembodiments, for example, the geometric features of certain zones mayimpact the size of the radii 116 within that zone. In portions of thestent 100 with relatively more connectors 120, less material may beavailable to allow for large radii 116. In one embodiment a stent 100may be designed such that the radii are from about 40 microns to about60 microns, including radii of about 54 microns, in portions of thestent 100 with about five connectors 120 around the circumference of thestent (such as most of the proximal zone, a of the illustrated stent100). Similarly, portions of the stent 100 with about 10 connectors 120around the circumference of the stent 100 may have radii 116 from about25 microns to about 45 microns, including radii of about 35 microns.Finally, portions of the stent 100 with about 20 connectors around thecircumference of the stent 100 may have smaller radii 116, such as fromabout 10 microns to about 20 microns, including radii of about 15microns. It will be appreciated by one of skill in the art having thebenefit of this disclosure that these values may vary in differingdesigns; for example, a stent 100 may be cut with a relatively largenumber of connectors 120, but with relatively narrow connectors 120 toallow more material for larger radii 116.

Each strut arm 114 may define a length along the strut arm 114. Again,as shown in both FIG. 1 and FIG. 1A, each strut arm 114 is coupled totwo other strut arms 114, forming apexes 115 on both ends of the strutarm 114. The length of a single strut arm 114 is the length of the strutarm 114 from a first end to a second end, or the distance between eachapex 115 at which the strut arm 114 is coupled to an adjacent strut arm114.

The relative lengths of the strut arms 114 may affect the overallproperties of the stent 100. For instance, portions of the stent 100that have relatively longer strut arms 114 may be “softer” (again,meaning more compressible in a transverse direction) than portions ofthe stent 100 where the strut arms 114 are relatively shorter. In theembodiment illustrated in FIG. 1, the stent arms 114 located adjacentthe proximal 102 and distal 104 ends are relatively longer than thosealong subsequent annular segments 112, moving toward the mid-body 103 ofthe stent 100. Thus, the stent 100 illustrated in FIG. 1 may be stiffer,or less compressible in a transverse direction, at the inner portions ofthe proximal α and valve γ zones, as compared to the portions of thesezones adjacent the proximal 102 and distal 104 ends of the stent 100.

In other embodiments, the stent 100 may also be configured such that thestrut arms 114 located near the proximal 102 end are relatively longerthan the strut arms 114 located near the distal 104 end. Accordingly,the stent 100 may also be softer near the proximal end 102 relative tothe distal end 104. In other embodiments, a stent may be designed withstrut arms of uniform length throughout, of a particular length alongcertain portions of the stent (for example, near both the proximal anddistal ends), or of varying lengths along the entire stent. Further, insome embodiments, strut arm 114 length will be substantially constantfor all strut arms 114 located on the same annular portion 112; in otherembodiments strut arm 114 length may vary within a single annularportion 112.

In some embodiments, a stent may be configured with softer zones inorder to tailor the stent to a specific therapy. For example, a stentdesigned with relatively soft ends may result in relatively lessdiscomfort, or pain, caused by contact of the stent ends with bodytissue. Thus, in some embodiments the portion of the stent 100configured to be implanted at the treatment location may be relativelystiff—allowing it to resist stricture and otherwise function as part ofthe treatment—while other portions are relatively soft to reduce traumaand pain at those points.

In certain embodiments, the strut arms 114 may be curved. Strut arm 114f illustrated in FIG. 1A, for example, may be understood as having afirst portion 117 and a second portion 118. The first 117 and second 118portions may or may not be the same length. Strut arm 114 f is generallyformed with an inflection point located between the first 117 and second118 portions of the strut arm 114 f. Thus, in the illustratedembodiment, the strut arm 114 f may be curved in the general shape of asigmoid curve. In other words, the first portion 117 of the strut arm114 f forms a first roughly arcuate path, and the second portion 118 ofthe strut arm 114 f forms a second roughly arcuate path. In theillustrated embodiment, the center of the first arcuate path is on theopposite side of the arm than the center of the second arcuate path.Thus, the strut arm 114 f has a wave-like shape formed by the strut arm114 f starting to curve in one direction, then curving in a seconddirection. Accordingly, strut arm 114 f has an “inflection point” at oraround the point where the first portion 117 meets the second portion118. In the embodiment of FIG. 1, each strut arm 114 is shapedsubstantially as described in connection with strut arm 114 f.

In other embodiments, the strut arms 114 may have a single curve, may besubstantially straight, or may resemble other types of curves.Furthermore, while in some instances each strut arm 114 may have acurved shape similar to the other strut arms 114 of the stent 100, inother embodiments multiple strut arms 114 on the same stent—includingstrut arms 114 disposed in the same annular segment 112—may havedifferent shapes.

As shown in FIGS. 1 and 1A, adjacent annular segments 112 may be coupledby connectors 120. In some embodiments, the connectors 120 may becoupled to the annular segments 112 at the apexes 115 formed by adjacentstrut arms 114. In the embodiment of FIGS. 1 and 1A, the connectors 120of adjacent annular segments 112 are aligned in the circumferentialdirection along the longitudinal direction of the stent 100 for all rowsexcept the three rows of annular segments 112 nearest the proximal end102 of the stent 100. In other embodiments, the connectors 120 may beoffset circumferentially along the longitudinal direction of the stent100, or aligned, along any longitudinal segment of the stent 100.

Furthermore, in certain embodiments, such as the embodiment of FIG. 1, astent 100 may be configured with different numbers of connectors 120 perannular segment 112, along the length of the stent 100. In theembodiment of FIG. 1, the stent 100 has more connectors 120 per annularsegment 112 in the valve zone γ than in the transition zone β, and moreconnectors 120 per annular segment 112 in the transition zone β and thevalve zone γ than in all but the first row of the proximal zone α.Specifically, the illustrated embodiment has about twenty connectors 120per annular segment 112 in the valve zone γ, about ten connectors 120per annular segment 112 in the transition zone β and about fiveconnectors 120 per annular segment 112 in all but the proximal-most rowof the proximal zone α. In other embodiments the absolute number ofconnectors in each zone may vary from these values, as may the ratio ofconnectors 120 per annular segment 112 in each zone.

The number of connectors 120 included in a particular zone may beconfigured to affect the properties of the stent 100 in that zone. Forexample, the proximal-most row of the stent 100 may be configured with10 or more connectors 120 to provide more uniform crimping as comparedto sections of the stent 100 with only five connectors 120 per annularsegment 112. In different embodiments, the number of connectors 120associated with any annular segment 112 may vary from about fourconnectors 120 per annular segment 112 to about 20 connectors 120 perannular segment 112.

In the illustrated embodiment, the stent has about ten connectorsconnecting the proximal-most annular segment 112 to the adjacentsegment. In other embodiments the stent 100 may be configured with thesame number (five, ten, or some other number) of connectors per annularsegment 112 throughout the entire proximal zone α.

In embodiments wherein the stent has more connectors at theproximal-most end than the rest of the proximal zone (such as theembodiment of FIG. 1), the greater number of connectors may beconfigured for a number of functions. For example, a greater number ofconnectors at the proximal end may be configured to add resiliency andstrength to the end of the stent. In particular, in embodiments wherethe ends of the stent flare out to relatively large diameters,additional connectors may add strength to minimize the potential forinfolding at the oversized end. Additionally, a larger number ofconnectors may be configured to provide for more uniform crimping of thestent in preparation for loading the stent into a catheter, and for moreuniform expansion upon deployment. Though the embodiment of FIG. 1 onlyhas additional connectors associated with the proximal-most annularsegment, in other embodiments a stent may have additional connectorsassociated with more than one row near the proximal end. For example,the first 1, 2, 3, 4, 5, or more proximal-most annular segments may beconfigured with additional connectors.

Further, in the illustrated embodiment, the connectors 120 linking thefirst three rows of annular segments 112, beginning with theproximal-most row 112, are offset circumferentially from each other.This alternating alignment of the connectors, as well as the thicknessof the scaffolding structure, may be configured to enable a stent, suchas stent 100, to resist infolding. For example, in some instances thealternating alignment of the connectors may tend to localize stentdeformation caused by strictures in the lumen, rather than transferringsuch deformations along the length of the stent. In some embodiments theconnectors may be offset at one or both ends of the stent 100 due toincreased concern for infolding at the ends of the stent 100. This maybe particularly true in stents 100 with flared ends, which have a moreopen (and therefore softer) scaffolding structure near the ends. Theillustrated embodiment has alternating connectors associated with thethree proximal-most annular segments; other embodiments may have more orfewer rows with alternating segments, including 1, 2, 3, 4, 5, or 6annular segments.

As with varying the lengths of strut arms 114, described above,variations in the number of connectors 120 per annular segment 112 mayaffect the relative hardness of the stent 100. Generally, portions ofthe stent 100 with a larger number of strut arms 114 per annular segment112 may be relatively harder than portions with fewer connectors 120.Thus, the stent 100 illustrated in FIG. 1 may be relatively harder inthe transition zone β and the valve zone γ than in the proximal zone α.In some embodiments this may provide additional support and strength tosupport the valve 150. The relative hardness of different portions ofeach zone may not be constant, however, due to other factors such asstrut arm 114 length, discussed above.

FIG. 1B is a close up view of a portion of the proximal zone α of thestent 100 of FIG. 1, showing a particular connector 120 a. The connector120 a couples two adjacent annular portions 112 d, 112 e together, andis coupled to each annular portion 112 d, 112 e at apexes 115 b, 115 con each annular portion. Connector 120 a has a first portion 122 a and asecond portion 124 a. In the illustrated embodiment, the first portion122 a is relatively straight and spans much of the distance between theadjacent annular segments 112. In other embodiments, the first portion122 a may be more or less curved than the first portion 122 a of theillustrated embodiment. The second portion 124 a may be substantiallyformed in a rounded shape, in some instances forming the general profileof the symbol omega (Ω). In some embodiments, the omega-shaped secondportion 124 a may add axial strength to the stent 100. In someinstances, axial strength may be desirable for repositioning or removinga stent 100.

Further, in some embodiments, omega-shaped connectors may addflexibility and/or elasticity to the stent 100. The omega shape, havingtwo ends relatively near each other connected by a relatively longcurved member (the round portion of the omega) may be configured toprovide added flexibility to the stent.

The other connectors 120 within the proximal zone α of the embodiment ofFIG. 1 are generally shaped like connector 120 a disclosed above, withthe exception of one row of connectors located at about the mid-body ofthe stent 100, as discussed in more detail below. It is within the scopeof this disclosure, however, to use any type or shape of connector atany point along the stent.

At the portion of the stent 100 shown in FIG. 1B, the adjacent annularsegments 112 d, 112 e are aligned such that apexes 115 at the peak ofthe zigzag pattern in annular segment 112 d are circumferentiallyaligned with apexes 115 at the peak of the zigzag pattern of theadjacent annular segment 112 e. The connector 120 a couples the twoadjacent annular segments 112 d, 112 e by coupling to valley apex 115 bof annular segment 112 d and to valley apex 115 c of annular segment 112e. (As used herein, “peaks” refer to high points and “valleys” refer tolow points, as measured from one end of the stent. Thus the coupling ofthe two segments just described may also be described as a “peak topeak” connection, if viewed from the opposite orientation.) In someembodiments, a stent may be designed such that the peaks and valleys ofadjacent annular segments are circumferentially aligned, such as annularsegments 112 d and 112 e. In other embodiments, the peaks and valleys ofadjacent annular segments may be circumferentially offset.

In the embodiment of FIG. 1, the peaks of each annular segment 112 areapproximately circumferentially aligned with the peaks of adjacentannular segments 112, at all points along the stent 100 except one setof adjacent annular segments located at the mid-body 103 of the stent100. FIG. 1C is a detailed view of two adjacent annular segments 112 f,112 g located near the mid-body 103 of the stent 100. (Note: Annularsegment 112 f of FIG. 1C is the same annular segment as annular segment112 e of FIG. 1B.)

Annular segments 112 f, 112 g are oriented such that the peaks ofannular segment 112 f are circumferentially aligned with the valleys ofannular segment 112 g, and the valleys of annular segment 112 f arecircumferentially aligned with the peaks of annular segment 112 g. Itwill be appreciated by one of skill in the art having the benefit ofthis disclosure, that in alternative embodiments any combination ofalignment/non-alignment of peaks and valleys between any set of annularsegments is within the scope of this disclosure.

Annular segments 112 f and 112 g are coupled to a connector 120 b atapex 115 d and apex 115 e, respectively. Connector 120 b extends betweeneach apex 115 d, 115 e and includes a generally U-shaped or squareportion 126 located near the center of the connector 120 b. Connectorssuch as connector 120 b, which span between a peak and a valley, may beconfigured to impart more flexibility to the stent 100 than relativelyshorter peak to valley connectors. As with the omega-shaped connectorsdisclosed above, it is within the scope of this disclosure to use aconnector with a square portion, such as connector 120 a of FIG. 1B, atany point along the stent.

FIG. 1D is a close up view of a portion of the valve zone γ of the stent100 of FIG. 1, showing a particular connector 120 c. Similar toconnector 120 a of FIG. 1B, The connector 120 c couples two adjacentannular portions 112 h, 112 i together, and is coupled to each annularportion 112 h, 112 i at apexes 115 f, 115 g on each annular portion.Again, similar to connector 120 a of FIG. 1B, connector 120 c has afirst portion 122 b and a second portion 124 b. In the illustratedembodiment, the first portion 122 b is relatively straight and spansmuch of the distance between the adjacent annular segments 112. In otherembodiments, the first portion 122 b may be more or less curved than thefirst portion 122 b of the illustrated embodiment. The second portion124 b may be substantially formed in a V-shape.

In some embodiments, such as the embodiment of FIG. 1, V-shapedconnectors may be used in place of, or in connection with, omega-shapedconnectors as described above. V-shaped connectors may be used in placeof omega-shaped connectors in applications where the additional axialstrength provided by omega-shaped connectors is not necessary; forexample, in the embodiment of FIG. 1 the axial strength provided by 20total connectors per annular segment may obviate the need foromega-shaped connectors for some applications. Further, V-shapedconnectors may reduce the force required to crimp a stent for loadinginto a catheter. Additionally, the shape of the connectors 120 may beinfluenced by the surrounding geometry of the stent 100. For example,the gap between adjacent annular segments 112 and the total number ofconnectors 120 per annular segment 112 may limit the amount of materialavailable to be shaped into a connector 120. In some embodiments, forexample, omega-shaped connectors 120 (which require relatively morematerial) may not be feasible in zones with a large number, such as 20,of connectors 120 per annular segment 112. V-shaped connectors 120(which require relatively less material) may be more feasible in suchzones.

In the embodiment of FIG. 1, omega-shaped connectors are utilized in thetransition zone β of the stent 100. It is within the scope of thisdisclosure to use any shape of connector within any zone, or to usemultiple shapes within the same zone.

The stent 100 of FIG. 1 further includes generally roundedanti-migration portions 128 coupled to certain apexes 115 within theproximal zone α. FIGS. 1A and 1E show close up views of anti-migrationportions 128, including anti-migration portion 128 a of FIG. 1E. In someembodiments, the anti-migration portion 128 a may be configured tocontact portions of the inside diameter of a body lumen, and thusrestrict migration of the stent 100 within the body lumen. The roundedhead 129 a of the anti-migration portion 128 a, may be from about 0.75mm in diameter to about 1.5 mm in diameter, including embodiments fromabout 1.0 mm to about 1.3 mm or embodiments with a diameter of about 1.2mm.

In certain embodiments, the anti-migration portions 128 may bepositioned such that the rounded head 129 is displaced outward of theoutside diameter of the stent 100. For example, anti-migration portion128 b of FIG. 1 is disposed outward from the outside diameter of thestent 100. This arrangement may allow anti-migration portion 128 b toengage the body lumen and minimize migration of the stent 100. In theembodiment of FIG. 1, each anti-migration portion 128 is disposedoutwardly as anti-migration portion 128 b, though in other embodimentsnot every anti-migration portion may be so disposed.

The total number of anti-migration portions may vary depending on thesize of the stent and the application for which it is configured. Forexample, an esophageal stent having a length of about 100 mm may includefrom about 15 to about 25 anti-migration portions, including about 20total anti-migration portions. Similarly an esophageal stent having alength of about 120 mm may include from about 25 to 35 anti-migrationportions, including about 30 total anti-migration portions, and anesophageal stent having a length of about 150 mm may include from about35 to 45 anti-migration portions, including about 40 anti-migrationportions.

In the embodiment of FIG. 1, each anti-migration portion 128 is disposedin a distally oriented direction, thus configured to minimize migrationof the stent 100 in the distal direction. In the case of an esophagealstent, such a design may be configured to counteract the peristalticforces of the esophagus. In other embodiments, some or all of theanti-migration portions 128 may likewise be disposed in the proximallyoriented direction.

The stent 100 of FIG. 1 further includes a covering 130 coupled to thescaffolding structure 110, the covering 130 defining an inner portion ofthe stent 100. The covering 130 may be elastomeric, polymeric, orcomprised of any other material known in the art. In some embodiments,the cover may include silicone, while in certain embodiments the covermay be comprised only of silicone.

In some embodiments, the cover 130 may be applied such that it tends toebb and flow into spaces between portions of the scaffolding structure110 of a stent, resulting in a “tire tread” like outer surface, ratherthan a smooth outer covering. In some embodiments such a design may beconfigured to allow tissue to lock into the uneven spaces and treads,thus adding anti-migration properties in some instances.

In some embodiments the cover 130 may include multiple subparts orlayers. For example, in some embodiments the cover 130 may be a two-partdesign. Such two-part covers may be composed of a base cover whichencapsulates the scaffolding structure 110 and a second cover which maybe applied after the first cover cures. In certain embodiments thesecond cover may only be applied to the outside diameter of the stent100 and may chemically bond to the first cover layer. For example, astent may have a covering with a first layer comprised of a medicalgrade silicone such as TSP-8021, and a second cover, applied to theoutside diameter of a particularly low friction silicone, such as NusilMED-6670. Multiple layered coverings may be configured such that theprimary layer adds elasticity or resiliency to the stent while thesecond, outer layer reduces friction along the outside diameter. It iswithin the scope of this disclosure to use any of the exemplarymaterials for any of the layers.

In embodiments which utilize a particularly low friction cover on theoutside diameter of the stent 100, the outer cover may be configured tomore easily allow the stent to be loaded into a catheter and/or todecrease the catheter size necessary to sheath the stent 100.Specifically, a low friction outer layer, such as Nusil MED-6670disclosed above, may reduce the coefficient of friction between acatheter and a stent by as much as 50% in some applications.

Further, an additional lubricant, such as Nusil MED-400, for example,may be utilized to increase the ergonomics of the system, allowing thestent 100 to be more easily loaded into, or deployed from, a catheter.In some embodiments silicone lubricants may be used, includingfluorinated polymers such as MED-400. Use of fluorination may reduce thesolubility of the lubricant in some silicone elastomers; thus use afluorinated lubricant may reduce the tendency of the lubrication todissolve into the silicone base over time.

Additionally, the stent 100 of FIG. 1 includes a suture 135 disposedadjacent the proximal end 102 of the stent 100. The suture 135 may beconfigured as a repositioning or removal aid, allowing a practitioner tocapture a deployed stent. In other embodiments the stent 100 may also oralternatively comprise a suture (not shown) disposed adjacent the distalend 104 of the stent 100.

The features and elements of the stent 100 of FIG. 1 may be configuredto create a stent with particular characteristics and features. Inaddition to the disclosure recited above, the disclosure providedhereinafter—in connection with any figure or discussion—is equallyrelevant to controlling the characteristics of a finished stent. Anypart of the present disclosure may be combined with any other part ofthe disclosure to configure a stent. Thus, while certain aspects orparameters—for example, strut arm length or flared ends—may be discussedin connection with one embodiment, such disclosure is relevant to allembodiments.

A stent with substantially the geometry and features described inconnection with the stent 100 of FIG. 1 may be configured to “neck down”in response to an axial force. In other words, the diameter of thecylindrical stent may be reduced by applying an axial force to thestent. Such necking down may be used in connection with removing orrepositioning a deployed stent; the decrease in diameter may pull thestent out of contact with the body lumen, allowing a practitioner todisplace the stent while avoiding some trauma to the body lumen.

In some instances this necking down may occur near the ends of thestent, including instances where the stent only necks down at one end ofthe stent. For example, a practitioner may reposition or remove a stentby first engaging a suture located near one end of the stent. At thesuture location the stent may decrease in diameter as force is appliedto the suture; in other words the stent may contract or “purse string”as the suture is tightened. In some embodiments the force associatedwith this purse string effect may be understood as a compressive forceacting around the circumference of the stent at the suture location.

Additionally, portions of the stent near the suture may neck down as anaxial force is applied to the stent, in some instances the stent neckingdown to a diameter which is less than the mid-body of the stent. In someembodiments, a stent may be configured such that a force of about 2pounds causes the stent to neck down as described.

In certain embodiments a stent may be configured to decrease in size,due to one or both of the purse string effect and necking down,primarily at the ends of the stent. In some instances, tissuegranulation or other tissue ingrowth into the stent may occur primarilyat the ends of the stent. Thus, some stents may be configured todecrease in diameter at the ends to allow a practitioner to dislodge thestent ends from the wall of the body lumen, including in cases wherethere is tissue granulation at the ends of the stent.

As stated above, each of the elements described above may be manipulatedto control the necking down characteristics of a stent. In particular, astent such as stent 100 of FIG. 1 may neck down due to the elasticity ofthe covering 130, the thickness of the scaffolding structure 110, andthe configuration of the geometry at the ends 102, 104 of the stent 100,including the inclusion of suture eyelets (discussed further below) andthe circumferentially alternating arrangement of certain connectors. Astent such as stent 100 may neck down as much as 50% in response to anaxial force.

A practitioner may begin the process of repositioning or removing astent, such as stent 100, by first engaging the sutures. The sutures maybe used to compress one end such that the end is pulled away from thelumen wall. The practitioner may then apply an axial force to the end ofthe stent, causing a portion of the stent to neck down and pull awayfrom the lumen wall. The practitioner may then reposition or remove thestent with minimal trauma to the body lumen.

Additionally, the increased number of connectors in the transition β andvalve γ zones may act to decrease infolding in these zones due to theincreased strength in the transverse direction associated with moreconnectors. Likewise, as discussed above, alternating connectors at theproximal end may be configured to aid with infolding.

FIG. 2 is a front view of another embodiment of a stent that can, incertain respects, resemble components of the stent described inconnection with FIGS. 1 and 1A-1E above. It will be appreciated that allthe illustrated embodiments may have analogous features. Accordingly,like features are designated with like reference numerals, with theleading digits incremented to “2.” (For instance, the stent isdesignated “100” in FIG. 1, and an analogous stent is designated as“200” in FIG. 2.) Relevant disclosure set forth above regardingsimilarly identified features thus may not be repeated hereafter.Moreover, specific features of the stent and related components shown inFIG. 2 may not be shown or identified by a reference numeral in thedrawings or specifically discussed in the written description thatfollows. However, such features may clearly be the same, orsubstantially the same, as features depicted in other embodiments and/ordescribed with respect to such embodiments. Accordingly, the relevantdescriptions of such features apply equally to the features of the stentof FIG. 2. Any suitable combination of the features, and variations ofthe same, described with respect to the stent and components illustratedin FIGS. 1 and 1A-1E, can be employed with the stent and components ofFIG. 2, and vice versa. This pattern of disclosure applies equally tofurther embodiments depicted in subsequent figures and describedhereafter.

FIG. 2 is a front view of another embodiment of a stent 200. The stent200 defines a proximal end 202 and a distal end 204 as well as amid-body section 203. In some embodiments the stent 200 may have asmaller diameter near the mid-body section 203 than sections of thestent 200 near the proximal 202 and distal ends 204. Thus, in theillustrated embodiment, D₂ and D₃ may be larger in magnitude than D₁. Insome embodiments, the mid-body diameter may be constant along a lengthof the stent 200, with flare portions that gradually increase indiameter near the ends 202, 204. Depending on the desired application,the diameters of the stent 200 may vary. For example, certain stents maybe designed with mid-body diameters of about 12 mm to about 25 mm,including stents with diameters from about 19 mm to about 23 mm. Inembodiments which include flared zones near the ends of the stent, thediameter of the flared sections may increase from about 2 mm greater toabout 8 mm greater than the mid-body diameter of the stent, includingincreases of about 4 mm to about 6 mm or an increase of about 5 mm orincrease of about 2 mm to about 4 mm, including increases of about 3 mm.While in some embodiments the stent 200 may increase by about the samemagnitude at both the proximal 202 and distal 204 ends, in otherembodiments, such as the embodiment of FIG. 2, the increases may bedifferent. For example, in the embodiment of FIG. 2, D₂, or the diameterat the proximal end, may be about 5 mm greater than D₁, the mid-bodydiameter of the stent 200, while D₃ may be about 3 mm greater than D₁.

In embodiments where the strut arms 214 are relatively longer (creatingrelatively “softer” zones near the ends 202, 204 of the stent 200) theflare section may correlate with the zones of the stent 200 that haverelatively longer strut arms 214. The strut arm 214 length may beconfigured to gradually increase along the longitudinal direction of thestent 200 in the flare zones.

Similarly, the length of the connectors 220 may gradually increase asthe strut arm 214 length increases. Longer connectors 220 and arm struts214 may generally create a more open scaffolding structure 210 near theends 202, 204 of the stent 200. In some embodiments, the flare zones maybe mirror images of each other; in other embodiments they may bedifferent.

In some embodiments, the flare zones may be formed by stretching orexpanding the ends 202, 204 of the stent 200 with respect to themid-body 203 of the stent 200. This may result in a more openscaffolding structure 210 near the ends of the stent 200. Regions of thestent 200 with a more open scaffolding structure 210 may be relativelysofter than regions of the stent 200 which have a denser scaffoldingstructure 210. Thus, the flared ends of a stent, such as stent 200, maybe configured to create a stent with ends which are softer than themid-body 203 of the stent. As disclosed above, relatively longer strutarms 214 and connectors 220 may also be configured to create softerregions on a stent. Flared ends and changing strut arm 214 and connector220 lengths may each be designed and/or may utilize independently from,or in connection with, these other parameters in order to create a stent200 with relatively softer, or stiffer, zones.

The stent 200 may be configured to neck down in a similar manner to thatdescribed in connection with the stent 100 of FIG. 1. In someembodiments, the flared portions of the stent 200 may be configured toneck down to a diameter less than the diameter of a mid-body section ofthe stent. In certain embodiments, a mid-body section may not beconfigured to neck down.

FIGS. 2A-2B are additional views of the stent 200 of FIG. 2. FIG. 2A isa top view of the stent of FIG. 2, viewing the stent 200 from theproximal end 202, and FIG. 2B is a cross-sectional view of the stent ofFIG. 2, taken through line 2B-2B.

As shown in FIG. 2 the stent 200 may include suture threading eyelets236 or apertures, coupled to one or more apexes 215 of the scaffoldingstructure 210 at the proximal 202 end of the stent 200. The suturethreading eyelets 236 may be configured to receive a suture 235 andcouple it to the stent 200.

Furthermore, the suture threading eyelets 236 may comprise holes orapertures which are elongated in the circumferential direction of thestent 200. Such a design may be configured to distribute the expansiveforce of a stent 200 acting on a body lumen when the stent 200 isdeployed. This distribution of force, in connection with the smooth androunded shape of the eyelets 236, may be configured to lessen the traumato body tissue which contacts the end 202 of the stent 200.

The suture threading eyelets 236 may be configured to locate the suture235 substantially at the proximal 202 end of the stent 200. In otherwords, the eyelets 236 may be positioned such that the entirescaffolding structure 210 is located distal of the eyelets 236. Suchpositioning may be configured to create a relatively uniform pursestring effect when the suture 235 is engaged. Thus, in some embodiments,the uniformity of the purse string effect may be influenced by theproximity of the suture threading eyelets 236 to the proximal end 202 ofthe stent 200. In other embodiments, the uniformity of the purse stringeffect may instead, or also, be due to the elongated nature of theeyelets 236 which may allow a suture 235 to more readily slide throughthe eyelets 236 during tightening.

In some ways analogous to the eyelets 236 at the proximal end 202, thestent 200 may be configured with rounded elongate knobs 246 coupled toone or more apexes 215 of the scaffolding structure 210 at the distalend 204 of the stent 200. In some aspects these knobs 246 may resemblethe shape of the eyelets 236 though there is no hole present in theknobs 246. Further, the knobs 246 may be larger or smaller than eyelets236 on the same stent 200, depending on stent design parameters, such asthe relative size and flare of the proximal 202 and distal 204 ends ofthe stent 200.

Similar to the eyelets, the elongated design of the knobs 246 may beconfigured to distribute the expansive force of a stent 200 acting on abody lumen when the stent 200 is deployed. This distribution of force,in connection with the smooth and rounded shape of the knobs 246, may beconfigured to lessen the trauma to body tissue which contacts the distalend 204 of the stent 200.

FIGS. 2A and 2B further illustrate a valve 250 coupled to the insidediameter of the stent 200. As shown in FIG. 2, the valve 250 may belocated within the valve zone γ of a stent 200, and may be positionedcloser to the distal end 204 of the stent 200 than to the proximal end202.

The valve 250 may be coupled to the stent 200 by one or more rows ofstitching 254 around the circumference of the stent 200. In otherembodiments the valve 250 may alternatively or additionally be coupledto the stent 200 through use of an adhesive, through welding, throughcaulking, and through other attachment methods. For example, in someembodiments the valve 250 may be positioned with the stent 200 prior toapplying a coating to the stent 200. Application of the coating mayserve to simultaneously bond the valve to the coating in some instances.

Further, the stent 200 may be configured with one or more marker eyelets248 coupled to the scaffolding structure 210 of the stent 200. In someembodiments there may be between 2 and 6 marker eyelets 248 around thecircumference of the stent, including embodiments with about 4 totalmarkers. A radiopaque tantalum (Ta) marker may be laser welded to one ormore of these eyelets 248 in some embodiments. In other embodiments, anymaterial which is visible for x-ray or fluoroscopic imaging may beused—for example, high density metals such as gold, platinum, tantalum,and so on. The marker may also or alternatively be riveted to theeyelets 248. A radiopaque marker may be utilized to position the stent200 within the body of a patient in some instances. In some instancesthe marker eyelets 248 may be positioned at the same longitudinallocation along the stent 200 as the proximal most edge of the valve 250.

FIGS. 2 and 2A also illustrate a suture 235 configured for use inconnection with the stent 200. The suture 235 may be configured to allowa practitioner to engage the suture 235 in order to aid in removingand/or repositioning the stent. In some instances this may beaccomplished by the practitioner grasping and displacing the suture 235through use of a remote access tool, such as grasping forceps. Thesuture 235 may be formed of a metal, a thread, or any other material. Insome embodiments, the suture 235 may comprise one or more radiopaqueportions 238 for use in deploying, removing, or repositioning a stent.The radiopaque portions may be formed of a metal, such as gold, andenable a practitioner to distinguish these portions by x-ray or similarmethods, thus allowing the practitioner to more easily capture suture235 of a deployed stent with a remote capturing tool. Similarly, thesuture 235 may also or alternatively comprise endoscopic markers, ormarkers visible through an endoscope, to aid a practitioner in viewingor manipulating the stent in connection with an endoscope. In someembodiments certain markers, such as markers comprised of gold, may beboth radiopaque and visible through an endoscope.

FIG. 3 is a perspective view of a portion of a stent 300 including avalve 350. The stent 300 has a distal 304 end, a covering 330, and ascaffolding structure 310. The stent 300 is oriented such that the valve350 is visible through the opening at the distal end 304 of the stent300. In other embodiments, the valve 350 may be positioned at otherlocations along the longitudinal length of the stent 300, includinglocations closer to the proximal end (not shown) of the stent 300.

FIGS. 4A-4D are multiple views of a valve 450 configured for use with astent. The valve 450 may be formed of an elastomeric or polymericmaterial and may comprise an upper surface 451, a lower surface 452, anda rim 453. The rim 453 may provide structure and support to the valve450 as well as providing a location at which the valve 450 may becoupled to a stent, for example, by stitching.

The valve 450 may further comprise an opening 455 which is closed whenthe valve 450 is not actuated. In the illustrated embodiment, the valveopening 455 comprises three intersecting slits in the valve body. Thevalve opening 455 may be opened in response to a force acting on theupper surface 451 of the valve 450. Likewise, the valve may be opened bya force acting on the lower surface 452 of the valve 450. The shape anddesign of the valve 450 may be such that the force required to open thevalve 450 by acting on the lower surface 452 is much larger than theforce required to open the valve 450 by acting on the upper surface 451.For example, FIG. 4D illustrates two forces, F₁ acting on the uppersurface 451 of the valve 450 and F₂ acting on the lower surface 452 ofthe valve 450. In response to F₁, the three-sided valve opening 455 mayrelatively easily open, as opposing sides of the opening 455 are pushedaway from each other. Contrarily, in order for F₂ to open the valve 450,the entire lower surface 452 must deform, folding in on itself until thevalve opening 455 is located on the opposite side of the rim 453. Thus,the valve 450 may be designed such that it is more easily opened in onedirection than the other.

In the case of esophageal stents, a valve such as valve 450 may bepositioned such that the lower surface 452 faces the stomach while theupper surface 451 faces the mouth. In this orientation, the valve 450may more readily open to allow food to pass to the stomach, butgenerally will prevent reflux from the stomach, except in response to arelatively large force—for instance when a patient belches or vomits.

Notwithstanding the specific disclosure provided in connection withFIGS. 4A-4D, it is within the scope of the current disclosure to utilizea stent with any type or design of valve, or without a valve at all.

In some embodiments, stents may be crimped and packed within a catheterby a manufacturer, prior to shipping. In other embodiments, stents maybe self-sheathing. As used herein, “self-sheathing” stents are stentsconfigured to be at least partially sheathed by a user, either in thecontext of initially sheathing a stent (for example prior to deployment)or in the context of sheathing a deployed stent for repositioning orremoval. Thus, in some embodiments, a stent may be configured such thatthe self-sheathing process does not deform or alter the stent in such asway as to limit the usability of the stent when subsequently deployed.In some embodiments, a self-sheathed stent may be configured such that auser may sheath the stent just prior to use. For embodiments whichutilize a valve, a stent may be configured to be, at least partially,self-sheathing to avoid deforming the valve for an extended period oftime. For example, a stent with a valve, such as valve 450, when crimpedand packed in a catheter for an extended period of time, may kink,crease, or otherwise plastically deform. Thus, in some embodiments, astent may be designed such that it is partially or fully self-sheathing,minimizing the time the valve is deformed within a catheter.Specifically, in some embodiments a stent may be designed such that aportion of the stent is crimped and loaded by a manufacturer, while theportion of the stent containing the valve is sheathed by the user justprior to use.

Referring back to FIGS. 1-1E, certain features of the stent 100 may beconfigured to allow the stent to be self-sheathing. Stent 100 may beconfigured such that a portion of the proximal zone α is crimped andsheathed within a catheter prior to use. Circumferentially alignedconnectors along portions of the proximal α, transition β, and valve γzones which are not pre-loaded into the catheter may be configured toprovide axial strength to the stent 100, allowing the remainder of thestent to be pulled into a catheter by the user without the stent 100deforming in the axial direction. A deployment device may be configuredto anchor to the stent at one or more points along the stent wherein theconnectors are circumferentially aligned. For example, stent 100, whichhas alternating connectors for the three proximal-most rows, may beconfigured to be anchored to the sheathing mechanism distal the thirdrow of annular segments. In some embodiments, a stent 100 may havecircumferentially aligned connectors along the entire length of thestent 100. In still other embodiments, all the connectors may be offset,or aligned in some zones and offset in other zones. In some instances,deployment devices may be utilized which are configured to grip thestent 100 at any point; aligned connectors may be optional in suchembodiments.

Moreover, the relatively large number of connectors 120 within the valvezone γ may be configured to aid in self-sheathing. In particular, alarge number of circumferentially aligned connectors may be configuredto provide axial and radial strength and stability duringself-sheathing. In some instances, the valve zone γ may be configured touniformly contract during self-sheathing, thus applying balanced forcesto the valve. In some instances this may mitigate potential deformationof the valve.

Similarly, the use of V-shaped connectors 120 within the valve zone maybe configured to aid in self loading of the stent 100. V-shapedconnectors may result in less friction between the stent and thecatheter during self loading as the angled portion of one side of the Vmay more easily slide into a catheter than an omega-shaped connectorwhere the catheter may become caught on the outwardly rounded portion ofthe omega shape.

Furthermore, the transition zone β may be configured such that thetransition between the softer proximal zone α and the harder valve zoneγ is not overly extreme; the transition zone β may be configured suchthat the axial and radial forces required for self-sheathing areuniformly transferred between the soft and hard zones of a stent.Furthermore, the transition zone β may be configured to provide uniformexpansion between the proximal α and valve γ zones during deployment ofthe stent.

In the embodiment of FIG. 1, no anti-migration portions 128 are locatedwithin the valve zone γ or the transition zone β. Thus, in theillustrated embodiment, all anti-migration portions 128 may be crimpedand loaded into the catheter by a manufacturer, minimizing the chance ofthe anti-migration portions catching on the edge of the catheter, orotherwise interfering with self-sheathing. In other embodimentsanti-migration portions 128 may be positioned at any point along thestent 100, including portions that are configured for self-sheathing.

FIG. 5 is a side view of a stent 500 in an unexpanded state. Moreparticularly, FIG. 5 is a side view of an unexpanded stent in a “rolledout” state, depicted as if the stent 500 were cut in the longitudinaldirection and rolled out flat such that the entire circumference of thestent 500 may be viewed flat.

In some embodiments, a stent 500 may be formed by cutting a pattern,such as that shown in FIG. 5, into a tube of material. In some instancesthe material may be a memory alloy, and the cutting may be accomplishedthrough use of a laser. The cut tube may then be stretched and expanded.The unexpanded stent of FIG. 5 has many similar features to the otherstents discussed herein, though the other stents were depicted inexpanded states.

As mentioned in connection with other embodiments, and as illustrated inFIG. 5, a stent 500 may be configured such that strut arms 514 towardthe ends 502, 504 of the stent 500 may be longer than strut arms 514disposed at or near the mid-body 503 of the stent 500.

In the illustrated embodiment, the stent 500 has twenty total rows ofannular segments 512. As illustrated, the rows of annular segments 512closest to either end are configured to comprise flared portions of anexpanded stent. In the illustrated embodiment, the strut arms 514 nearthe ends 502, 504 of the stent 500 are relatively longer than the strutarms 514 located near the mid-body 503 of the stent 500. A wide varietyof strut arm 514 lengths is within the scope of this disclosure. Forexample, in some instances the strut arm 514 lengths may vary along thelength of the stent 500 from strut arm 514 lengths of about 4 mm toabout 5.25 mm.

In the illustrated embodiment, the stent 500 is configured with about 20pairs of strut arms 514 on each row around the circumference of thestent 500. The total number of strut arms 514 around the circumferencemay be influenced by the geometry of the stent 500; for example, thenumber of connectors, strut arm width, and size of the inside radii mayall impact the total number of strut arms 514 which may be disposedabout the circumference of the stent 500. Similarly, the desired angleof each apex may impact the number of strut arms 514 which may bedisposed about the circumference of the stent 500. For example, for apexangles of about 30 degrees there may be between about 16 and about 24pairs of strut arms 514 disposed about the circumference. For apexangles of about 60 degrees there may be between about 18 and about 22pairs of strut arms 514 disposed about the circumference. In theillustrated embodiment, configured for apex angles of about 45 degrees,there are about 20 pairs of strut arms 514 about the circumference. Insome embodiments any of these parameters, including the number of strutarms 514 and apex angle, may vary in different zones of the same stent500.

In the illustrated embodiment the flare sections begin about 4 rows inon the proximal end 502 of the stent and about 5 rows in on the distalend 504 of the stent 500. In other embodiments the flare sections may bemore or less than this, including embodiments where the flare sectionsare from about 2 rows to about 8 rows long including from about 4 rowsto about 6 rows. In the illustrated embodiment, the relative length ofthe strut arms 514 gradually increases at the beginning of each flaresection of the stent 500 moving toward either end 502, 504. For example,in one embodiment the lengths of the strut arms 514 may be about 4 mm atthe beginning of each flare section, and gradually increase to about5.25 mm near the proximal 502 or distal 504 ends of the stent 500. Inother embodiments the strut arms 514 may likewise vary from about 4.25mm to about 5.0 mm, or from about 4.5 mm to about 4.75 mm. In stillother embodiments, the stent 500 may be designed such that the strut arm514 lengths in a particular zone of the stent 500 are constant andgradually change in other zones. For instance, in some embodiments, arelatively long stent may be formed by forming a mid-body 503 sectionwith a constant strut arm 514 length and gradually increasing the strutarm 514 length in flare sections adjacent the ends 502, 504 of the stent500. Numerous stent lengths are within the scope of this disclosure,including, for example, stents from about 70 mm to about 150 mm inlength, including stents from about 100 mm to about 120 mm in length.

FIGS. 5A-5D are detailed views of portions of the unexpanded stent ofFIG. 5. These figures show the relative position of the strut arms 514,suture threading eyelets 535, marker eyelets 548, connectors 520, andanti-migration portions 528 when the stent 500 is in an unexpandedstate.

As shown in FIGS. 5 and 5A the relative size of the suture threadingeyelets 535 may be related to the total number of eyelets and thediameter of the tube of material from which the stent 500 is cut. Insome embodiments, the eyelets may be shaped with the maximum elongationin the circumferential direction allowed by the number of eyelets 535and the circumference of the tube. Similarly, and referring also to FIG.5D, in some embodiments the rounded elongate knobs 546 may be sized aslarge as possible given the diameter of the material from which thestent 500 is formed. Again referring to the illustrated embodiment,adjacent knobs 546 and/or eyelets 535 may be offset along thelongitudinal direction in order to allow for relatively larger knobs 546and/or eyelets 535. The illustrated embodiment has knobs 546 and eyelets535 at two longitudinal positions; in other embodiments the knobs 546and/or eyelets 535 may all be in-line or may be disposed at more thantwo longitudinal positions. In some instances the stent 500 may beformed from a tube of material having a diameter from about 3 mm toabout 8 mm, including from about 4 mm to about 6 mm or about 5 mm.

FIG. 5C is a close up view of a portion the stent of FIG. 5, showing onepossible relationship between a marker eyelet 548 and surroundingconnectors 520 in an unexpanded state. In the illustrated embodiment,the second portion of certain connectors near the marker eyelet 548 mayhave a less pronounced shape due to the use of material for the markereyelet during the cutting process. For example, second portions 524 aand 524 b are straighter, having less of a V-shape, than surroundingconnectors, thus allowing for more material to be used to form themarker eyelet.

Numerous sizes and configurations of stents are within the scope of thisdisclosure. By way of example, and not limitation, in addition toesophageal stents, the current disclosure is also applicable to biliarystents and other stents which may utilize a valve. In some embodimentsthis disclosure may be used with such stents in the following sizes anddimensions. Biliary stents: mid-body diameters from about 6 mm to about11 mm including diameters of about 8 mm to about 10 mm; flare sectionsconfigured to expand from about 0.5 mm to about 2 mm in diameter greaterthan the mid-body diameter of the stent; and lengths of from about 40 mmto about 100 mm, including lengths from about 60 mm to about 80 mm.

FIG. 6 is a cross-sectional view of a stent 600 deployed within a bodylumen 50. The stent comprises a scaffolding structure 610, a covering630, a suture 635, and a valve 650.

In some instances the body lumen 50 may be the esophagus. In theseinstances, a variety of stent placements are possible, includingplacements where a portion of the stent 600 at the distal end 604extends into the stomach. In some instances, for example, the valve 650may be aligned with the lower esophageal sphincter and the distal end604 of the stent 600 positioned within the stomach. In otherembodiments, the valve 650 may be aligned with the lower esophagealsphincter with the distal end 604 of the stent 600 located proximal tothe stomach or flush with the stomach.

The examples and embodiments disclosed herein are to be construed asmerely illustrative and exemplary, and not a limitation of the scope ofthe present disclosure in any way. It will be apparent to those havingskill with the aid of the present disclosure in the art that changes maybe made to the details of the above-described embodiments withoutdeparting from the underlying principles of the disclosure herein. It isintended that the scope of the invention be defined by the claimsappended hereto and their equivalents.

1. An implantable device having a generally cylindrical shape,configured to be disposed within a body lumen, the device comprising: ascaffolding of struts, comprising: a plurality of annular segmentsdisposed along the circumference of the cylindrical shape, the segmentsarranged in rows in the longitudinal direction of the cylindrical shape,each annular segment comprising a plurality of interconnected arms; aplurality of connectors extending between and interconnecting adjacentannular segments; wherein the annular segments and connectors of theimplantable device define a proximal zone adjacent the firstlongitudinal end of the cylindrical shape, a valve zone adjacent asecond longitudinal end of the cylindrical shape, and a transition zonelocated between the valve zone and the proximal zone, each zonecomprising a plurality of annular segments, wherein the transition zoneis more compressible in a transverse direction than the valve zone, andwherein the proximal zone is more compressible in the transversedirection than the transition zone, and a valve coupled to an insidediameter of the cylindrical shape, the valve disposed within the valvezone.
 2. The implantable device of claim 1, wherein adjacent arms of theplurality of interconnected arms are arranged at acute angles relativeto each other.
 3. The implantable device of claim 1, further comprisinga plurality of eyelets, elongated in a circumferential direction of thecylindrical shape, the eyelets configured to receive a suture, and theeyelets disposed adjacent a first longitudinal end of the cylindricalshape.
 4. The implantable device of claim 1, further comprising apolymeric cover coupled to the scaffolding of struts.
 5. The implantabledevice of claim 1, further comprising a plurality of rounded knobs, theknobs elongated in a circumferential direction of the cylindrical shape,and the knobs disposed adjacent a second longitudinal end of thecylindrical shape.
 6. The implantable device of claim 1, wherein aplurality of arms is curved and has an inflection point.
 7. Theimplantable device of claim 1, wherein one or more connectors comprisean omega-shaped portion.
 8. The implantable device of claim 7, whereinone or more connectors comprise a V-shaped portion.
 9. The implantabledevice of claim 1, wherein one or more connectors within the valve zonecomprise a V-shaped portion.
 10. The implantable device of claim 1,wherein the device is configured with a greater number of connectors perrow of annular segments in the valve zone compared to the transitionzone, and a greater number of connectors per row of annular segments inthe transition zone compared to the proximal zone.
 11. The implantabledevice of claim 10, wherein two or more adjacent rows of connectorswithin each zone are circumferentially aligned.
 12. The implantabledevice of claim 11, wherein a plurality of rows of connectors within theproximal zone are circumferentially aligned with connectors disposed inadjacent rows and one or more rows of connectors within the proximalzone are not circumferentially aligned with one or more adjacent rows ofconnectors.
 13. The implantable device of claim 1, wherein a pluralityof annular segments is configured to reduce in diameter in response toan axial force applied to the implantable device.
 14. The implantabledevice of claim 1, wherein the device has a longitudinal length fromabout 70 mm to about 150 mm.
 15. The implantable device of claim 1,wherein the device has a mid-body diameter of about 12 mm to about 25mm.
 16. The implantable device of claim 1, wherein the angles at whichadjacent interconnected arms are joined in the proximal zone are largerthan the angles at which adjacent interconnected arms are joined in thetransition zone, and wherein the angles at which adjacent interconnectedarms are joined in the transition zone are larger than the angles atwhich adjacent interconnected arms are joined in the valve zone.
 17. Theimplantable device of claim 1, wherein annular segments of the proximalzone have fewer interconnected arms than annular segments of thetransition zone, and wherein annular segments of the transition zonehave fewer interconnected arms than annular segments of the valve zone.18. The implantable device of claim 1, wherein adjacent annular segmentsof the proximal zone are interconnected with fewer connectors of theplurality of connectors than adjacent annular segments of the transitionzone, and wherein adjacent annular segments of the transition zone areinterconnected with fewer connectors of the plurality of connectors thanadjacent annular segments of the valve zone.
 19. The implantable deviceof claim 1, wherein one or more connectors disposed in the proximal zonehave a first shape and one or more connectors disposed in the transitionzone have a second shape that is different from the first shape, andwherein one or more connectors of the valve zone have a third shape thatis different from both of the first shape and second shape.
 20. Animplantable device comprising: a scaffolding of struts disposed betweena first longitudinal end of the implantable device and a secondlongitudinal end of the implantable device, the scaffolding of strutsdefining a proximal zone adjacent the first longitudinal end of theimplantable device, a valve zone adjacent the second longitudinal end ofthe implantable device, and a transition zone located between the valvezone and the proximal zone, wherein the transition zone is morecompressible in a transverse direction than the valve zone, and whereinthe proximal zone is more compressible in the transverse direction thanthe transition zone, and a valve coupled to an inside portion of theimplantable device, the valve disposed within the valve zone.